Vinyl chloride polymers containing potassium zinc cuprocyanide

ABSTRACT

A new compound potassium zinc cuprocyanide has superior properties as a fire and smoke retardant in vinyl chloride polymers and provides non-discoloring formulations when tin mercaptide stabilizers are used.

United States Patent MeRowe 1 Jan. 21, 1975 VINYL CHLORIDE POLYMERS [56] References Cited CONTAINING POTASSIUM ZINC OTHER PUBLICATIONS CUPROCYANIDE Combustion and Flame 14, 85 to 96 (1970), Ameri- [75] Inventor: Arthur W. McRowe, Akron, Ohio can Elsevier Pub. Co.

[73] Assignee: lgerkB.NF;1G0odrich Company, New Primary Examiner v P Hoke Attorney, Agent, or Firm-J. Hughes Powell, Jr. [22] Filed: Oct. 19, 1973 21 Appl. No.: 407,863 [57] ABSTRACT A new compound potassium zinc cuprocyanide has superior properties as a tire and smoke retardant in 2% 260/4575 423/371 %?5: vinyl chloride polymers and provides non-discoloring E gz' formulations when tin mercaptide stabilizers are used.

3 Claims, N0 Drawings VINYL CHLORIDE POLYMERS CONTAINING POTASSIUM ZINC CUPROCYANIDE BACKGROUND OF THE INVENTION Improving the fire resistance and retarding smoke formation of polymers is highly desirable, particularly in polymeric materials used in applications in upholstery, rugs, furniture, structural materials in homes and other buildings and in automobiles, busses, planes, trains, ships and the like. While vinyl chloride polymers have resistance to flame, improvement of this property and reduction of smoke formation is desirable for safety and health reasons.

SUMMARY OF THE INVENTION A new compound, potassium zinc cuprocyanide, KZnCu(CN).,, is readily prepared which has superior properties as a fire and smoke retardant in vinyl chloride polymers.

DETAILED DESCRIPTION Potassium zinc cuprocyanide is readily prepared for example by dissolving cuprous cyanide in water containing three molar equivalents of potassium cyanide. To this clear solution there is added one molar equivalent of zinc acetate in water. A white precipitate immediately forms which is filtered, washed and dried.

Powder X-ray defraction of the dried powdered material shows it to be a highly crystalline compound and not a mixture of KCN Zn(CN) CuCN, KCu(CN) Zn(CN) l(,,Zn(CN), CuCN or any other mixture. Zinc cyanide, potassium zinc cyanide complexes and potassium copper cyanide complexes are water soluble. This new compound is water insoluble. Zinc cyanide and potassium zinc cyanide complexes decompose in hydrochloric acid. This compound is insoluble in and inert to hot concentrated hydrochloric acid. Analysis by X-ray fluorescence shows 14% potassium and equal amounts of copper and zinc.

This new compound is particularly useful as a tire and smoke retardant in vinyl chloride polymers in amounts from about 0.1 to weight parts per 100 weight parts of vinyl chloride polymer added normally as a fine powder. Such vinyl chloride polymers are normally high molecular weight materials having a specific viscosity above 0.4 measured as a 0.4 measured as a 0.4 percent solution in nitrobenzene include those vinyl chloride polymers well known to those skilled in the art as polyvinyl chloride as well as those containing vinyl chloride and up to about 50 percent by weight of other vinylidene monomers containing at least one terminal crn=o The vinyl chloride polymers will be mixed in addition to the KZnCu(CN)., with standard compounding ingredients known to those skilled in the art, plasticizers, lubricants, stabilizers, fillers, colorants, processing aids and the like by known methods.

EXAMPLE I 5.0 grams of cuprous cyanide was dissolved in 120 ml. water containing 11.58 grams of potassium cyanide. To this clear solution there was added 12.25 grams of zinc acetate in 50 ml of water. A white precipitate immediately formed which was filtered, washed and vacuum dried for 20 hours at 60C. The yield of 13.8 grams of KZnCu(CN) was 89+ percent of theoretical. The powder X-ray defraction showed a crystalline compound. The compound was insoluble in water and inert to hot concentrated hydrochloric acid. Analysis by X-ray fluorescence showed 14% potassium and equal amounts of copper and zinc.

EXAMPLE II To demonstrate the fire and smoke retardant properties of this compound, the following formulation was prepared by powder blending: parts by weight of polyvinyl chloride (Geon 103EP), 2 parts by weight of dibutyltindithioglycolate stabilizer and 3 parts by weight of polyethylene having specific gravity of 0.924g/cc and melt index of 5 g/lO minutes with 0, 0.5 and 5.0 parts by weight of the potassium zinc cuprocyanide.

The preblended mixtures were milled on a 2 roll mill at 330F. for 3 minutes after banding. The samples were sheeted off the mill to 78 mil thickness and were press molded at 350F. for 5 minutes and cooled under pressure to give white sheets 6 x 6 x 0.075 inch in size. There was no brown discoloration of the sample that normally is obtained when both a copper compound and the tin mercaptide stabilizer are present in polyvinyl chloride. 6 X A X 0.075 inch test specimens were cut for smoke-oxygen index measurements.

The smoke-oxygen index measures the mass loss rate, which is related to the burning rate, and a smoke rating determined by the ratio of rate of smoke production measured by optical density to the mass loss rate. The smoke-oxygen index is the Oxygen Index ASTM D2863 test method modified by means of the apparatus described by Dipietro et al, Journal of Fire and Flammability, Volume 2, Page 36, 1971. The following results were obtained.

Oxygen Smoke Smoke of Sample Index Rating Control Control 44.0 450 100 0.5 KZnCu(CN) 50.4 206 45.8 5.0 KZnCulCNh 54.6 184 40.9

per weight parts of a vinyl chloride polymer.

2. The composition of claim 1 wherein the vinyl chloride polymer is polyvinyl chloride.

3. The composition of claim 2 wherein there is from 1 to 5 weight parts of KZnCu(CN 

2. The composition of claim 1 wherein the vinyl chloride polymer is polyvinyl chloride.
 3. The composition of claim 2 wherein there is from 1 to 5 weight parts of KZnCu(CN)4. 